Vertical form fill and seal continuous and intermittent pouch machines are known in the art. Generally, they receive a continuous film and form the film into a film tube (i.e., the film is formed and sealed to have a closed cross section) about a forming tube. The forming tube typically has a circular or oval cross section, although other cross sections have been used. The film is continuously or intermittently fed around the forming tube and sealed vertically to form the film tube. The vertical seal is typically a lap seal or a fin seal.
Forming tubes can include ploughs or tucker bars to form pleats or creases that can be used to form gussets, to make stand-up pouches. The plough or tucker bar applies tension in an inward direction creasing the film tube. Forming plates may be provided on either side of the plough, applying tension in an outward direction. Two ploughs centered about a single tucker bar will form a “W” shaped gusset. The ploughs and tucker bars may be fixed in one location, such as at the bottom of the forming tube, or moveable in any direction. Examples of a tucker bar and forming plates may be seen in U.S. Pat. No. 6,679,034, hereby incorporated by reference. Tucker bars (and forming plates) may be used on a single side of the pouch, forming one gusset, or on opposing sides, forming two gussets. Forming tube assemblies may be changed out to form bags of other sizes. Another prior art machine is shown in U.S. Pat. No. 6,691,491, hereby incorporated by reference.
After the film tube passes the forming tube and tucker bar(s) it moves vertically downward to a sealing zone. Seal bars intermittently create a horizontal seal. The seal bars may be rotary, and can be in pairs to increase machine speed. An example of seal bars is given in U.S. Pat. No. 6,519,922, hereby incorporated by reference.
The horizontal seal forms the top seal of the pouch below the seal, and the bottom of the pouch above the seal. After the seal is formed a scale or other input device drops a predetermined amount of product through the forming tube. At the same time the film tube is advancing downward. When the subsequent seal is formed the product is below the sealing zone. The seal is formed, forming the top seal of the filled pouch and the bottom seal of the pouch above, thus sealing the product into the pouch. Stripper bars, such as those shown in U.S. Pat. No. 6,519,922 may be used to help ensure the product is below the sealing zone when the seal is made.
Different types of pouches may be formed with vertical form filling seal continuous packaging machines, such as pillow bags, stand up pouches, other pouches, etc. Standup pouches are typically formed with a gusset at (what will be) the bottom of the pouch using ploughs and a tucker bar as described above. For example, a pouch made on a vertical pouch machine may have a gusset put on one vertical edge of the pouch. However, when the pouches are separated from one another they are rotated 90 degrees so that what had been the vertical edge (with the gusset) of a pouch becomes the bottom edge of the pouch. The standup pouches look and perform well when one seal is placed at the bottom of each of the outer folds of the gusset. (The gusset is usually formed to be a “W” with the outer folds being the folds the pouch stands on.) However, prior art machines have not been able to reliably place a seal and typically tried to create the seal as the gusset is being formed. It is difficult with such an arrangement to change features of the pleat, such as depth or location, the entire forming assembly was changed out. Accordingly, a vertical form fill and seal pouch machine that provides a gusset with a pleat and seal on the outer folds of the gusset is desirable. Also, such a pleat should be easily adjustable.
When forming a seal on the bottom of the gusset, a pleat may be formed to locate the seal. However, the film can be difficult to crease without damaging the film. Accordingly, a vertical form fill and seal pouch machine that provides for pleating the film without damaging it is desirable.
Stand up pouches are typically formed such that the two sides of the gusset are equal in length. This results in a bag that stands upright. However, other gusset designs may be useful, such as one where the backside of the gusset is shorter than the front side, so that the pouch tilts away from the consumer or on the shelf. It is desirable to be able to control the depth and location of pleats and seals used to form a gusset, so that the gusset is thereby adjustable. Accordingly, a vertical, form fill and seal pouch machine that provides for adjustable seals and pleats on the gusset is desirable.
Standup pouches and are sometimes displayed to the consumer by hanging them from a rod through a hanger hole punched in the top of the pouch. Holes have been punched in pouches using horizontal machines and using intermittent vertical machines. It is desirable to provide a hole punch in continuous vertical machines, but thus far a hole punch that may be operated fast enough and with sufficient accuracy has not been available. Accordingly, in continuous vertical form fill and seal machine that provides a hole punch in what will be the top of a pouch is desirable.